Swim for your Life!

Killer Whale: MojosCoast

By Shannon Lyday

We were headed west out of Half Moon Bay just after dawn aboard the sanctuary research vessel Fulmar when Research Coordinator Jan Roletto shouted “killer whales!”  The team on the flying bridge immediately roused from our observer positions to look off the port side of the boat.  Splashes, white water and boils were less than 1,000 meters from our vessel.   We saw several dorsal fins and fluke slapping.  Commotion immediately broke out as we radioed to the bridge to stop the boat.

A moment later, we saw an animal bobbing at the surface in the middle of the white water and realized it was a harbor seal…and it was still alive!  The boat turned towards the action, and as soon as the harbor seal saw us it darted for the boat.  In its panic to escape the killer whales, the terrified seal was using its foreflippers in a butterfly stroke to get to safety. 

We all groaned as one of the female killer whales lunged at the seal and just missed.  As the seal reached our aluminum hull it realized that it was too high above the water line for it to reach.  It disappeared from our view and we wondered if the seal had met what we thought was its inevitable fate. 

The pod of seven killer whales, including one bull male, 2 calves and four female types (females or immature males) continued to approach and swim under the boat in search of the seal.  One calf was so small that it swam with it mother the entire time.  The larger calf would break off from the group to “play” – breaching and splashing.  The bull male kept the furthest distance from the boat, slowly circling us.  We then realized that the harbor seal was hiding in the space between the two catamaran hulls.  In our excitement to watch the whales, we had provided the seal a brief place of refuge.

After 45 minutes, the killer whales swam away and we returned to our transect line. As we looked back, there was no sign of the seal.  Perhaps the adults were only training their young and the seal escaped. Or perhaps a few whales were still lingering in the water.

The killer whale pod was later identified as a “transient” pod – indicated by their closed saddle patch (the white patch on the back behind the dorsal fin).  Transients are known to cooperatively hunt mammals. 

Killer whales are the largest of the toothed whales and are highly social animals.  Although they are widespread throughout the world’s oceans, sightings of this cetacean are considered rare in the Gulf of the Farallones National Marine Sanctuary.  This past weekend however, a whale watch trip saw a pod of 40+ killer whales by the Farallon Islands.

 

The Sanctuary Ecosystem Assessment Surveys conduct pelagic surveys of birds and marine mammals on designated transect lines throughout the sanctuary.  For more information about this research program, click here.

 

Photos: Harbor seal; orca mother and calf: S Lyday.